drilling through hulls

[Jono]

I've got a few questions on drilling some through hulls above and below the waterline for ballast on a super sport.
First the intakes below the waterline. I know the general idea - hole saw in reverse until you get through the gel. Establishing the exact place to drill is the nail biter as far as i can tell. I've heard of the use of magnets to locate the hole. In this case I'll be going on the opposite side of the raw water intake, beside the transmission. Would it not be OK to drill a 1/4" pilot hole from the inside of the boat? Then of course get underneath and finish with the hole saw? It seems more precise than lining up magnets.
When I am drilling above the waterline in the neighborhood of the bilge through hulls, there is a carpeted 'false wall' on the inside. Should I just drill through from the outside like its not even there? Or should I be somehow taking this down. Don't know if thats possible or necessary.
Lastly, I'll be starting out with 2 pumps, and I'll add the third down the road. So as far as intakes go, like i said previously, they will be beside the tranny opposite the raw water intake. I plan to have the 2 intakes for the rear bags there. When I add the third intake for the center locker, where is the best place for that one? Along with the other 2? I can't really go on the other side of the transmission where the raw water intake is. That intake has the hull formed for it, and there is some kind of plate running up to it, not leaving any room for anything. Would having 3 intakes in a row weaken the hull? Would that many cause draft issues?

Thanks for any input

[Chexi]

Okay, here we go. *takes deep breath*

1. Use some super strong little magnets. You cannot get more precise than that. If you must drill a pilot hole from inside out (good luck getting drill in there btw), then do so AFTER you do the magnets. Just make a template bigger than the thru-hull threaded part to make sure you have clearance and a flat surface on both inside and outside of hull. Note, you will be drilling a pilot hole with your hole saw from the outside in any way. If you are going all the way through either way, a hole is a hole is a hole. You can screw up on the bottom as easy as you can on the top, as there are non-flat surfaces and obstructions on the bottom too.

2. Use 1 bigger thru-hull (1.5"), or 2 (1") at the most. Don't use 3. There is no need. Then you can put a T on 1 of them, cap it, and you are ready to expand later (easily). If you go 1 total thru-hull, you need a cross or 2 Ts. Be sure the entire apparatus will fit before drilling the hole. The ball valve handles can be removed for installation.

3. No, you will mess up the carpet. Drill your pilot holes from outside in through the carpet. Locate pilot holes. Use razor knife or similar to cut carpet. Then drill rest of thru-hull with hole saw from outside in.

4. Tape all gelcoat before drilling with hole saw, even if going in reverse.

5. Chamfor the gelcoat to avoid spider cracking.

6. Measure 11x before cutting anything.

[wake_fun]

Read my Perfect Pass install thread for magnets and cutting the hole.
You only need one thru hole for your ballast system.

[Jono]

I've read every thread on ballast intalls until my brain turned into a jumbled mess. I'll have to go back an re-read how and why to have just the one through hull. I've had wakemakers help me with this, and they suggested each bag gets their own through hull to fill and drain from. Can anyone shorten the search for me and link me to the appropriate thread on how to build the manifold and where to mount it?
The less I have to drill in the bottom of the boat the easier it is for me.

[wake_fun]

Did you look at my signature?

[Chexi]

Wake_fun's thread is the bomb. Reading it made me everything I am today... well okay not everything I am today, but it sure helped me with my ballast install projects.

The only things I do not remember seeing in his thread are the following (please forgive me Wake_fun if they are there):

1. Chamfor the gelcoat around all thru-hull holes to avoid spider cracking.
2. Chris-cross your vent lines (rear starboard bag vent to the port side and vice versa) to avoid siphon problems when surfing.

Wakemakers is a good outfit. I use them for almost all my parts. However, I disagree with whoever there told you that 3 holes is necessary or even preferable. I also disagree with their calculations on what you need for a manifold size if you go with 1 hole. Pi R squared is the formula for area, and application of that simple formula will tell you that a 1" thru-hull is enough for 3 bags that run off impeller pumps with 1/2" inside diameter openings (it's actually mathmatically enough to just barely run 4 if there are no hard corners in the plumbing, but that is too close for my comfort). The math proves it.

I am assuming you are using ballast puppies, although if you are using aerators, then you don't have to worry about burning up impellers due to lack of water volume anyway.

[wake_fun]

Wake_fun's thread is the bomb. Reading it made me everything I am today... well okay not everything I am today, but it sure helped me with my ballast install projects.

That was great! It made me LOL